80. The number of participants has d_________ to 50, which we didn’t expect.

79. He d_______ the reward as he has devoted his whole life to this course(事业).

78. It is our duty to take every possible measure to protect the e_________ animals.

77. You had better s_______ the steps of operating the machine so that everybody can learn them quickly and accurately(准确地).

76. Could you explain to us the s__________ and differences between these books?

请根据句子的逻辑含义，用恰当的词的正确形式填空，并把完整的单词写在答题卷标号为75-84相应的空格上。

75. As is known to all, IQ stands for i_________ quotient.